This invention relates to a refrigerant compressor for compressing refrigerant circulating within an air conditioning system mainly adapted for use in vehicles, and more particularly to a refrigerant compressor of this kind which is capable of efficiently separating lubricating oil from the refrigerant in which the oil is entrained.
Vane compressors are widely used for compressing refrigerant circulating within air conditioning systems for vehicles, by virtue of their structural simplicity and high adaptability to high speed operation. In such vane compressors, an appreciable amount of lubricating oil is mixed in the refrigerant gas for lubricating and cooling of the sliding parts of the pump assembly of the compressor so as to avoid seizure of such sliding parts during high speed operation, etc. However, if the refrigerant gas contains lubricating oil in too large quantities, the evaporator and condenser of an air conditioning system fail to fully exhibit their respective functions of evaporating and condensing the refrigerant gas, resulting in a drop in the thermal efficiency of the air conditioning system. To avoid such inconvenience, conventional refrigerant compressors of this kind in general are provided with lubricating oil-separating devices arranged in their discharge pressure chambers for separating lubricating oil from the discharge refrigerant. A most diffused type of such lubricating oil-separating devices is formed by an oil-separating gauze for separating the oil from the refrigerant through collision of the refrigerant against the gauze. Besides this type, there have been proposed a variety of oil-separating devices of this kind, such as a cyclonic type, a surface tension-collecting type, and a gravity-precipitating type.
However, few of such proposed types can steadily achieve a high rate of oil separation against fluctuations in the rotational speed of the compressor or fluctuations in the discharge pressure of same, and few of them can be compact in size but can exihibit an efficient oil-separating function so as to cope with a limited mounting space within the compressor. Particularly in the collision-separating type using a gauze, etc., the oil-separating rate drops in a high rotational speed region of the compressor.